Water-soluble carboxymethylcellulose is an anionic polymer useful in many industrial processes and consumer products. It has traditionally been handled in its dry, particular form. Problems associated with dry water-soluble carboxymethylcellulose include undesirable dust generation, poor dispersibility when added to aqueous systems, and undesirably long dissolution times.
The dust associated with dry, particular water-soluble carboxymethylcellulose presents the same conventional handling problems as are encountered with similar particular materials. One major concern is the possibility of dust explosions.
Water-soluble carboxymethylcellulose is hygroscopic and absorbs water from the air, which can cause particle agglomeration. Such agglomerated particles are very difficult, if not impossible, to disperse in an aqueous system.
When added to aqueous systems, water-soluble carboxymethylcellulose tends to agglomerate or form clumps. Agglomeration can be reduced in many cases by adding the polymer to the aqueous system slowly with agitation. Slow dissolution substantially reduces the speed of manufacturing operations.
For the above reasons, plant operators desire a fast, effective and simple way of incorporating water-soluble carboxymethylcellulose into an aqueous system. That is, users of water soluble carboxymethylcellulose desire a stable, concentrated, aqueous water-soluble polymer carboxymethylcellulose suspension that can be used to incorporate water-soluble carboxymethylcellulose in aqueous solutions readily, without formation of agglomerates or clumps, and which may be handled without the problems associated with drypowder water-soluble carboxymethylcellulose polymers.
Girg et al, in U.S. Pat. No. 4,283,229, disclose that a stable suspension can be prepared by adding a nonionic, water-soluble cellulose ether derivative to a solution of 4 to 12% of an electrolyte if alumina is added to the suspension. Suitable electrolytes are described to include metal or ammonium salts of mineral acids or organic acids, especially salts which contain an alkali metal ion, an alkaline earth metal ion, an earth metal ion, or a zinc, copper, iron or manganese ion as the cation, and a sulfate, carbonate, silicate, sulfite, halide, phosphate, nitrate, nitrite, acetate, formate, tartrate, or citrate ion, including their hydrogen satls, as the anion. Examples V1 and V2 show dispersion of 25% by weight methylhydroxyethylcellulose using 28 and 20% by weight potassium carbonate, respectively.
The inventor has studied dispersion of anionic, water-soluble carboxymethylcellulose and discovered that high levels of this polymer can be dispersed in an aqueous system using certain levels of potassium carbonate.